When using particle analysis equipment such as turbidimeters with flow through cells in industrial applications, the build-up of material on the optical windows of the cell can seriously degrade performance. In the past, manual cleaning systems have been relied upon which generally are inconvenient in many instruments. Also, there have been proposed automated systems utilizing electrically or hydraulically operated cleaning devices. In those situations the hydraulic or electric material has been located externally of the cell and required a liquid seal where the motion required by the cleaning device passed through the wall of the sample cell.